1// Copyright 2016 Google Inc. All rights reserved. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15package android 16 17import ( 18 "fmt" 19 "strings" 20 "unicode" 21 22 "github.com/google/blueprint/proptools" 23) 24 25// ExpandNinjaEscaped substitutes $() variables in a string 26// $(var) is passed to mapping(var), which should return the expanded value, a bool for whether the result should 27// be left unescaped when using in a ninja value (generally false, true if the expanded value is a ninja variable like 28// '${in}'), and an error. 29// $$ is converted to $, which is escaped back to $$. 30func ExpandNinjaEscaped(s string, mapping func(string) (string, bool, error)) (string, error) { 31 return expand(s, true, mapping) 32} 33 34// Expand substitutes $() variables in a string 35// $(var) is passed to mapping(var), which should return the expanded value and an error. 36// $$ is converted to $. 37func Expand(s string, mapping func(string) (string, error)) (string, error) { 38 return expand(s, false, func(s string) (string, bool, error) { 39 s, err := mapping(s) 40 return s, false, err 41 }) 42} 43 44func expand(s string, ninjaEscape bool, mapping func(string) (string, bool, error)) (string, error) { 45 // based on os.Expand 46 buf := make([]byte, 0, 2*len(s)) 47 i := 0 48 for j := 0; j < len(s); j++ { 49 if s[j] == '$' { 50 if j+1 >= len(s) { 51 return "", fmt.Errorf("expected character after '$'") 52 } 53 buf = append(buf, s[i:j]...) 54 value, ninjaVariable, w, err := getMapping(s[j+1:], mapping) 55 if err != nil { 56 return "", err 57 } 58 if !ninjaVariable && ninjaEscape { 59 value = proptools.NinjaEscape(value) 60 } 61 buf = append(buf, value...) 62 j += w 63 i = j + 1 64 } 65 } 66 return string(buf) + s[i:], nil 67} 68 69func getMapping(s string, mapping func(string) (string, bool, error)) (string, bool, int, error) { 70 switch s[0] { 71 case '(': 72 // Scan to closing brace 73 for i := 1; i < len(s); i++ { 74 if s[i] == ')' { 75 ret, ninjaVariable, err := mapping(strings.TrimSpace(s[1:i])) 76 return ret, ninjaVariable, i + 1, err 77 } 78 } 79 return "", false, len(s), fmt.Errorf("missing )") 80 case '$': 81 return "$", false, 1, nil 82 default: 83 i := strings.IndexFunc(s, unicode.IsSpace) 84 if i == 0 { 85 return "", false, 0, fmt.Errorf("unexpected character '%c' after '$'", s[0]) 86 } else if i == -1 { 87 i = len(s) 88 } 89 return "", false, 0, fmt.Errorf("expected '(' after '$', did you mean $(%s)?", s[:i]) 90 } 91} 92